Abstract
This paper presents new research on a lacustrine anoxic event (LAE). These data include stable carbon isotope (δ13Corg), pyrite sulfur isotope (δ34Spy), trace element and biomarker ratios from the Hongmiaozi Basin (North China) and unravel the response of continental lakes under the influence of early Aptian extreme climate conditions. According to the stratigraphic chronology (122–118 Ma) and carbon isotope correlations, terrestrial sediment was influenced by the early Aptian Oceanic Anoxic Event (OAE1a). The results show that the Xiahuapidianzi Group experienced a significant warming process under negative excursions in carbon isotopes due to the influence of increased carbon dioxide partial pressure (pCO2). The climate varied from warm and humid to hot and arid (high Sr/Cu, low Rb/Sr, calcareous mudstone), the evaporation and salinity increased (high Sr/Ba and B/Ga), and land input sources decreased (low Zr, Ti and Th). Moreover, high total organic carbon (TOC) content was source from bacteria, algae (n-alkanes), and euxinic depositional environments (Pr/Ph, Cu/Zn and U V Mo). In the stage of continuous carbon isotopes positive excursion, organic matter accumulated rapidly. A paleolake environment model has provided a better understanding of current global climate issues under global warming caused by increased carbon dioxide concentrations.
Highlights
The distinctive features of the Cretaceous period are global warming, bio-events, shale deposition in marine environments due to intermittent oceanic anoxic events (OAEs) and associated isotopic anomalies[1,2]
Organic stable carbon isotope and pyrite sulfur isotope methods are widely used for explaining environmental changes, bottom-water anoxia and sedimentary environment conditions[1,12,13], and trace elements are essential in deciphering the depositional environment[14]
We report a new lacustrine anoxic event (LAE) under the influence of the global oceanic anoxic event 1a (OAE1a) event
Summary
The distinctive features of the Cretaceous period are global warming, bio-events, shale deposition in marine environments due to intermittent oceanic anoxic events (OAEs) and associated isotopic anomalies[1,2]. OAE1a is characterized by sedimentary organic matter (Livello Selli) and dramatic fluctuations in the carbon isotope records of carbonate and organic carbon (δ13Ccarb and δ13Corg)[2]. These carbon isotope (δ13C) fluctuation records have been interpreted as evidence of perturbations of the global carbon cycle[2,3,4]. Organic stable carbon isotope and pyrite sulfur isotope methods are widely used for explaining environmental changes (including climate change), bottom-water anoxia and sedimentary environment conditions[1,12,13], and trace elements are essential in deciphering the depositional environment[14]. These early achievements act as a foundation for oil and gas exploration and development work
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